三峡水库建成后长江中下游防洪战略思考

三峡水库建成后，长江中下游防洪形势显著改善，但由于经济社会发展，防洪要求的提高和江湖关系的变化，长江防洪形势发生了一些新的变化。以1954年和1998年典型大洪水为例，分析了三峡水库建成后长江中下游防洪形势出现的新变化，讨论了长江中下游蓄滞洪空间格局调整及江湖关系变化对于防洪的影响。根据长江水沙变化、河道演变、水库群调控和分蓄洪区使用几率变化等出现的新问题，提出未来防洪战略及对策。结果表明:三峡建成后，百年一遇以下洪水防御形势明显好转，而百年一遇以上特大防洪的防洪形势仍然严峻，洪水风险主要转移到水库群上；今后需要在加强蓄滞洪区建设的基础上，重点推动防洪非工程措施建设，以减轻特大洪水带来的灾害损失。

An approach on flood control strategy in middle and lower reaches of Yangtze River after the completion of the Three Gorges Dam project

The completion of the Three Gorges Dam project would result in significant improvements in the flood control of the middle and lower reaches of the Yangtze River. However, additional flood control measures would be needed to address population and economic growth along with a more prominent role of reservoirs in attenuating floods. These measures were addressed herein by considering scenarios post dam construction, and using as input the historic and extremely large floods of 1954 and 1998. The locations of the storage areas and flows between the rivers and lakes within the basin were considered along with other key factors affecting flood control. In addition, new issues were considered, such as chemical runoff, sediment transport and subsequent river evolution, reservoir regulation, and alteration of the probability of flood storage. The results showed that the construction of the Three Gorges Dam would improve flood control for the 100-year and more frequent event. However, the results showed that flood controls would not greatly affect the flooding resulting from larger flood. It was also observed that the flood risk was transferred to the reservoirs (or lakes). Therefore, to mitigate flooding from extremely large floods, more effort needs to be put on increasing flood control measures in the reservoirs using both structural and non-structural approaches.